Central Nervous System Lesions: Correlation of Intraoperativeand Final Diagnoses, Six Year Experience at a Referral Centre in a Developing Country, Pakistan

Background and Aims: Intraoperative consultation of CNS lesions provides accurate diagnosis toneurosurgeons. Some lesions, however, may cause diagnostic difficulty. In this study accuracy of intraoperativeconsultations of CNS lesions and discrepancies in diagnosis and deferrals were analysed.
Methods: All CNScases from May 1, 2004 to September 20, 2010 in which intraoperative frozen section had been performed, andwhich were reported in the Section of Histopathology, Aga Khan University Hospital, Karachi Pakistan wereretrieved. The diagnoses given on FS were compared with the final diagnosis given on permanent sections (andadditional material if received), as indicated in the frozen section and final pathology report.
Results: Duringthe study period, 171 CNS cases were received for intraoperative consultation. In all cases, cryostat sections (FS)plus cytology smears were prepared. The ages of the patients ranged from 03 to 77 years. 106 were males and65 were females. Out of these 171 cases, 160 cases (94.1 %) were concordant, 10 cases (5.8 %) were discrepant,and one case was deferred until permanent sections. The diagnostic accuracy of frozen section was 88.9%. Thesensitivity and specificity were 94.8% and 87.5% respectively. The positive predictive value was 98.6% andnegative predictive value was 63.6%. All our cases in which intraoperative consultation was requested were sentfor primary diagnosis. Adequacy per se was not a criterion for sending cases for intraoperative consultation.
Conclusions: Our results show a reasonably high percentage of accuracy in the intraoperative diagnosis of CNSlesions. However, there are limitations and some lesions pose a diagnostic challenge. There is a need to improveour own diagnostic skills and establish better communication with neurosurgeons.